We recently demonstrated that serum obtained from patients with cystic fibrosis (CF) promotes the labelling of normal human leukocytes with extracellular (45Ca). The major objective of this current investigation is to determine if this effect of CF serum on calcium metabolism in normal human leukocytes is due to the presence of a unique factor in CF serum which alters calcium uptake or calcium efflux to increase the total intracellular calcium pool size thereby altering cyclic nucleotide levels and prostaglandin synthesis in the affected leukocytes. Data obtained from this investigation may explain why secretory cell activity is altered in CF patients. A mixed leukocyte fraction is isolated from whole blood drawn from normal individuals and incubated in the presence of CF serum or normal serum in a balanced Kreb's-Ringer bicarbonate buffer system at 37 degrees under 95% O2 and 5% CO2. Calcium binding is examined using extracellular (45Ca). Calcium uptake is examined using extracellular (45Ca) coupled with a lanthanum wash. Calcium efflux is examined using (45Ca)-labelled leukocytes. Total intracellular calcium pool size is examined using an atomic absorption spectrometer following a lanthanum wash. Cyclic AMP, cyclic GMP and prostaglandin E are quantified using radioimmunoassay. Asthmatic serum is also analyzed for the presence of a calcium transport factor to determine if the CF serum calcium transport factor may be unique to patients with CF or if its production could possibly be linked to pulmonary dysfunction.